Common Buckthorn | Keweenaw Invasive Species Management Area (KISMA)

Rhamnus cathartica

Characteristics

Common buckthorn, a woody shrub/small tree in the Rhamnaceae family, is an understory invasive that produces large amounts of seeds and out-competes many native species. It’s also both sun and shade tolerant and can live in many different soil, moisture, and habitat conditions. Identifying features include:

dark-green, oval leaves with a toothed margin and veins that bend towards the tip
stems are brown, turning gray with age, and covered in very prominent lenticels
females produce numerous black, round, bird-dispersed drupes that are persistent through winter
small, green-yellow flowers, clustered, with four petals

Note: This plant can be confused with native cherries like pin cherry and choke cherry. Note that cherries will have two black spots (glands) on the leaf petiole (stem) near the base of the leaf and buckthorn will not.

For more information visit Woody Invasives of the Great Lakes (WIGL) Collaborative and Midwest Invasive Species Information Network (MISIN).

common buckthorn leaves — Oval-shaped leaves and mature fruit of common buckthorn

Image credit: Sigrid Resh

common buckthorn in the winter — Drupes persist on branches through the winter

Image credit: KISMA

common buckthorn fruits — Black round drupes on female tree

Image credit: Sigrid Resh

KISMA Management Practices

Buckthorn is a highly aggressive species that produces copious amounts of seeds and saplings and is able to take over an understory relatively fast. Here at KISMA, buckthorn is another major invasive species that we have at multiple sites. It’s important to revisit sites as buckthorn seeds are viable in the ground for multiple years and it’s important to remove all seedlings. KISMA prioritizes removal of seed trees and satellite populations first, to prevent further spread of buckthorn.

hand-pull small seedlings and saplings
for stems too large to hand-pull, use a weed wrench to loosen the roots. After roots are loosened the tree should be easy to remove with hand pulling
if the tree is too large for the weed wrench, cut the tree a few inches above the ground and cover with thick trash bag, secure bag to stump with zip tie, spread bag over soil around stump, and weigh bag down with rocks or wood. Leave bag in place for two growing seasons. This smothering technique will prevent stump sprout regeneration and kill the root mass.

Note: It's very important to remove seeds and seed-bearing trees first, as this is the main reproduction strategy of buckthorn.

black plastic bag to smother cut stumps — Securely fastened plastic bag used to smother buckthorn stump sprouts after cutting

Image credit: Sigrid Resh

Native Alternatives

Great native alternatives to common buckthorn would be the native cherries like pin cherry (Prunus pensylvanica) and choke cherry (Prunus virginiana). Serviceberry (Amelanchier sp.) is also a great alternative providing a well needed food source to native wildlife. Other species like highbush cranberry (Viburnum trilobum) and other native shrub species are great as well.